Earthquake Recovery Minister Gerry Brownlee says the Canterbury Home Repair Programme (CHRP) is "one of the best examples of asbestos investigation and management in New Zealand".

"EQC firmly believes the Canterbury Home Repair Programme has not exposed Canterbury residents to any more risk than anyone else in New Zealand where work on asbestos-containing materials is being carried out in homes," he said.

"I applaud EQC and Fletcher EQR for introducing practices and standards in repairing houses that exceed guidelines issued by the relevant authorities, including introducing mandatory testing."

Brownlee's statements come on the back of revelations that authorities dealing with Christchurch's rebuild were still discussing the best way to handle asbestos in quake-damaged homes in late 2012, documents show.

Documents and emails provided to The Press show WorkSafe New Zealand, the Earthquake Commission (EQC) and other agencies were continuing to discuss the best strategy for handling asbestos as late as December 2012.

One email, sent on November 12, 2012 and released with the author's named blacked out, said the author continued to receive reports of damaged ceilings being covered with jib by unregistered tradesmen under the authority of EQC/EQR.

''You mentioned in August that there were up to 600 properties a month being treated this way. While the practice itself is probably illegal ... it also presents a huge public health risk.''

The presence of asbestos was ''rarely'' put on a property's LIM, the email stated.

''If an electrician turns up in 10 years time to insert down lights in a ceiling which has been disguised by jib, not only will they be putting themselves unknowingly at risk, but also any children playing in the dust generated.''

On November 16, 2012, Francois Barton of the Ministry of Business, Innovation and Employment (then known as the Department of Labour) sent an email stating that concerns about the future risk for trades people and residents in homes where asbestos had been covered-up ''have some validity''.

An email sent in response on November 21, 2012, said the author agreed the concerns ''have validity'' as there was ''no absolute safe level of asbestos''.

The author, who said their role was to ''advise the MBIE about medical issues'', said they agreed with Canterbury medical officer of health Alistair Humphrey, who had been calling for a register of buildings containing asbestos.

However, the author did not know whether current legislation ''allows for this to happen''.

Another email sent on November 26, 2012, stated the author met with Barton who agreed it would be useful to have a register of properties containing encased asbestos ''so that tradesmen could easily identify such asbestos up to decades hence''.

Another email on January 9, 2013, stated EQC agreed that concerns about future disturbances of ceilings where people were not aware of asbestos was ''definitely a valid worry''.

An email from a Ministry of Health staffer on March 15, 2013, said the risk for future homeowners was an issue that still ''has not yet been resolved''.

''EQC provides advice to the current home owner, but we did note that there is nothing really to make the current home owner pass it on to the next home owner.''

The Government and Fletcher Building this week said asbestos had been handled responsibly and the fact there had been only six investigations by WorkSafe from 100,000 home repairs showed the problem was not typical of Christchurch's rebuild.

A Fletcher EQR spokesman said the company had a policy of testing for asbestos in quake-damaged areas since the start of its repair programme, but in 2012 made testing compulsory in all houses built between 1940 and 1990.

The company was confident no-one would end up needing support for asbestos-related health issues, but support systems were in place, he said.

''We are not aware of any situation likely to lead to that sort of development . . . given the range of measures in place to prevent it.''